Super unprofessional. After a series of interviews, I was given a loose verbal offer and told a written offer would be sent to me within two days. The letter never showed up and they wouldn't answer phone calls or respond to emails. They then re-posted the job a few days later. Beware of these guys. Two on-site interviews in Chicago, two phone calls, and a trip out to a 3rd party consulting firm to take an 8 hour lab examination. Highly unusual.